Jet propulsion plant



May 19, 1970 c. D. HOPE-GILL 3,512,717

' JET PROPULSION PLANT Filed June 12, 1968 4 Sheets-Sheet l I N VEN TOR CHARLES DAVID HOPE-GI LL Attorney May 19, 1970 .c, PE- I 3,512,717

JET PROPULSION PLANT Filed June 12, 1968 4 Sheets-Sheet '2 INVENTOR CHARLES DAVID HOPE-GILL Attorney Filed June 12. 1968 y 1970 c. D. HOPE'GILL 3,512,717

JET PROPULSION PLANT 4 Sheets-Sheet 5 /5'/Z INVENTOR CHARLES DAVID HOPE-GILL May 19, 1970 c. 0.. HOPE-GILL 3,512,717

JET PROPULSION PLANT Filed June 12, 1968 4Sheets-Sheet 4.

INVENTOK CHARLES vnvm HOPE-GILL BY ATYORNEYS United States Patent 3,512,717 JET PROPULSION PLANT Charles David Hope-Gill, 1580 Jamaica Square, North Tonawanda, N.Y. 14120 Continuation-impart of application Ser. No. 589,752, Oct. 26, 1966. This application June 12, 1968, Ser.

Int. c1. B64c 9/00 U.S. Cl. 239-26537 16 Claims ABSTRACT OF THE DISCLOSURE To deflect the jet from a jet nozzle in a jet propulsion power plant, a deflector member is located behind the jet nozzle wholly or partially within the normal flow path of the jet; the deflector'extends between laterally spaced boundary walls and presents a convex longitudinal profile curved in a direction away from the jet so that the jet stream tends to follow the curvature of the surface. The transverse profile of the deflector surface matches the cross sectional shape of the jet.

CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my copen'ding application No. 589,752 filed Oct. 26, 1966 for Jet Propulsion Plant, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to jetpropulsion power plant, including gas turbine jet propulsion engines and rockets, and is concerned particularly with means for controlling the reaction jet issuing from a jet nozzle in such plant. The invention is applicable to jet propulsion plant for fixed wing aircraft, vertical take-01f and landing aircraft, ground effect machines, and in general to any power plant having a jet nozzle in combination with a jet deflector.

-' Jet deflectors normally consist of deflector members or conduits having reaction surfaces against which a jet stream impinges and which deflect or guide the jet stream in the required direction. With such known jet deflectors the required change of direction of the jet stream cannot be achieved without considerable loss of momentum in the jet itself.

It is an object of the present invention to provide a jet deflector suitable for use in conjunction with a jet engine power plant, wherein the loss of momentum is minimized; in favourable circumstances the effective momentum of the jet may even be augmented.

SUMMARY OF THE INVENTION The invention utilizes the principle of the Coanda effect, by which a high speed stream of gas flowing over a surface having a convex profile tends to follow the curvature of the surface. This effect is caused by a lowering of the static pressure of the gas adjacent to the surface to a value less than that of the enveloping gas.

A jet deflector according to the present invention essentially comprises a member having a surface with a convex profile curved in a direction away from the impinging gas stream whereby the gas stream attaches itself to the surface by the Coanda effect.

It should be remarked that the Coanda effect vanishes at the boundary edges of a gas stream impinging on a surface, at which edges there is no movement of the gas over the surface, giving rise to edge effects which tend to reduce the area over which the pressure differential is maintained. In the hypothetical case in which the gas stream is substantially two dimensional, impinging upon or flowing across the surface as a sheet of wide transice verse dimension but little depth, such edge effects are negligible. In the case of a jet issuing from a jet nozzle, however, the cross sectional shape of the jet approximates to the shape of the nozzle opening, and in general the edge effects cannot be ignored. In order to minimize these edge effects, and so increase efiiciency, a deflector according to the present invention may have laterally spaced boundary walls between which the jet is directed, and between which the profiled surface of the deflector extends. Preferably, the transverse profile of the deflector surface, or of the surface and boundary walls together, is matched to the cross sectional shape of the jet.

The lowering of the static pressure, in the case of a thick jet issuing from a jet nozzle as opposed to a twodimensional gas stream, is intensified due to the fact that when a primary gas stream impinges upon such a surface which in part obstructs the free flow of the gas stream, the part of the stream adjacent to the surface is accelerated, thus decreasing the static pressure. The result is that the increased pressure difference allows a jet stream of substantial thickness to attach itself to the surface, following the curvature of the surface, and detaching itself therefrom at a position at which the required pressure differential is insufllcient to maintain the attachment. Such a position may be at or just before a transverse discontinuity in the surface, such as a terminal edge, or a region at which the curvature increases above a critical value.

BRIEF DESCRIPTION OF THE DRAWINGS Illustrated embodiments of the invention will now be described with reference to the accompanying drawings, in which the same reference numerals are used to denote like parts, and in which:

FIG. 1 is a side elevation, partly broken away, of a jet deflector mounted on a jet propelled aircraft, the deflector being in the inoperative position;

FIG. 2 shows a detail of FIGURE 1 when the deflector is in an operative position;

FIG. 3 is an end view of the assembly shown in FIG. 2;

FIG. 4 is a sectional elevation of the details shown in FIG. 2;

FIG. 5 is a side elevation, partly in section, of a modified deflector having a shroud member, the deflector being mounted on a jet propelled aircraft and being shown in the inoperative position;

FIG. 6 is an end view of the assembly shown in FIG. 5;

FIG. 7 is a view similar to FIG. 5 showing the deflector in an operative position;

FIG. 8 is a side elevation, partly in section, of a further deflector according to the invention, the deflector being shown in a first operative position;

FIG. 9 is an end view of the assembly shown in FIG. 8;

FIG. 10 is a view similar to FIG. 8 showing the deflector in a second operative position;

FIG. 11 is a view corresponding to FIG. 2, of a modification of the invention;

FIG. 12 is an end view of the modification shown in FIG. 11; and

FIGS. 13 and 14 show a detail of yet another modification of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 to 4, an engine forming part of the jet propulsion unit of an aircraft has a generally barrel-shaped body 10 mounted beneath the wing 11 of the aircraft and supported therefrom by a rigid vertical web 12. The engine includes a jet nozzle having a longitudinal axis, which in the drawings is horizontal, the nozzle having a rearwardly directed discharge opening 13.

The discharge opening 13 is circular and the jet issuing therefrom is of generally circular cross section, the boundary or envelope of the jet being indicated in the drawings by ghost lines.

A jet deflector assembly 14, for controlling the direction of the jet, is mounted at the rearward end of a support structure 15 which is articulately connected to the body 10. The support structure 15 comprises a pair of arms 16 and 17 pivoted to the body by pivots 18 and 19, and extending rearwardly from the body so that the jet deflector assembly 14 lies behind the discharge opening 13 of the jet nozzle. The support structure can be moved about the pivots 18 and 19 by power operated means, shown in the drawings as hydraulic jacks 20 whose piston rods 21 are operatively connected to the arms of the support structure 15 at 22, so as to raise and lower the jet deflector assembly 14 into and away from the jet stream.

The jet deflector assembly itself comprises a deflector element 23 mounted between the support arms 16 and 17 and adjustably rotatable relative thereto about an axis 24. The deflector element has a surface 25 which in longitudinal section presents a convex profile curved away from the jet stream, the curvature of the surface decreasing continuously from a maximum at a region 25a to a minimum immediately adjacent a transverse discontinuity in curvature 25b, which provides a detachment edge for the jet stream. The transverse profile of the surface 25 is concave, as best shown in FIG. 3, the surface profile being part circular and the surface extending transversely between a pair of laterally spaced boundary walls 26 and 27 into which it merges. The transverse profile of the surface is such as to match the surface to the cross sectional shape of the jet stream, which in the present instance is circular. For other shapes of discharge opening 13 the surface 25 would be correspondingly profiled.

Power means for adjustably rotating the deflector element 23 about the axis 24 comprise a hydraulic jack 28 mounted in the support structure 15 and connected to one end of a cable 29 which passes round a pulley 30 fixed to the deflector element, the other end of the cable being connected to the support structure through a return spring 31.

In the view shown in FIG. 1 the support structure 15 is lowered to bring the jet deflector to an inoperative position at which it has no effect on the jet issuing from the jet nozzle; as indicated by the ghost lines, the jet is undeflected. Actuation of the ram 20 rotates the support structure about the pivot 18 to bring the jet deflector to the operative position shown in FIGS. 2, 3 and 4. When the jet deflector is in an operative position, the jet is directed between the boundary walls 26 and 27 and impinges on the surface 25. The jet stream attaches itself to the surface, following the curvature thereof, and detaches itself at or before the detachment edge 25b. It will be seen that the angular deflection of the jet will depend upon the position of the detachment edge 25b, which can be varied by adjustably rotating the deflector element about its axis 24, thereby varying the effective length of surface across which the jet stream flows.

In the modification shown in FIGS. 5, 6 and 7, the deflector element 23 is combined with a shroud member 32 which shouds the part of the surface 25 across which the jet stream is caused to flow, the shroud member defining with the surface 25 and the boundary walls 26 and 27 between which the surface extends, a passage for the entrainment of air. The shroud member 32 has a trailing edge 33 and a leading edge 34 in the form of an inwardly directed lip. The form of the lip 34 is such as to increase the amount of air entrained by the shrouded jet, and the total thrust of the jet is appreciably increased. As in the preceding example, the jet deflector assembly 14 is mounttd at the rearward end of a support structure 15, which is articulately connected to the engine body 10 at 18. The support structure can be raised and lowered by power operated means 20 to bring the jet deflector assembly from the inoperative position of FIG. 5 to the operative position shown in FIG. 7. Rotation of the deflector element about its axis relative to the support structure, in order to vary the deflection of the jet stream, is effected by an electric motor 35 coupled to a Worm drive 36. The shroud member 32 may be structurally combined with the deflector member shown, or alternatively be a separate structure which encloses it.

FIGS. 8, 9 and 10 illustrate yet another modification in which the deflector element comprises two telescoping sections 37 and 38, which are biased towards their telescoping position by means of a return spring 39. The outer section 37 is fixed in the support structure, and the inner section 38 is rotatable about a transverse axis 24 by means of a worm drive 36 to which is coupled an electric motor 35. Each of the sections has a surface which presents a convex profile curved in a direction away from the jet; the surfaces extend transversely between laterally spaced boundary walls 26 and 27, between which the jet is directed so that the jet stream tends to follow the curvature of the surfaces. In this modification the surfaces are part-cylindrical, but it will be understood that they may have a transverse profile to match the cross sectional shape of the jet, if desired, as in the preceding examples. The deflector assembly is mounted at the rearward end of a support structure 15 articulately connected to the engine body .10 at 18, and can be moved into and out of its operative position by power operated means 20.

If desired the jet deflector assembly and the support structure and associated parts may be combined in a single unit assembly mounted on the engine body 10 for rotation about the longitudinal axis of the nozzle. Further power operated means may be provided for effecting such rotation. By rotatably adjusting the support assembly and the deflector carried thereby about the longitudinal axis of the jet nozzle, the direction of the deflected jet, when the deflector is in the operative position, may be selectively adjusted.

In the modification illustrated in FIGS. 11 and 12, in which parts corresponding to the parts shown in FIGS. 1 to 4 are given the same reference numerals, a troughshaped member 1 having a concave upper surface and a convex lower surface cooperates With the jet deflector 14, the member 1 being disposed in the jet stream issuing from the discharge opening 13. The member 1 is positioned so that its lower surface 25 is either spacd by a small amount from or touches the surface of the jet deflector. Under suitable conditions, with member 1 present, the flow becomes more strongly attached to the jet deflector surface. A thrust augmentation of approximately 10% has been indicated when a gap exists between members 1 and 25. A possible reason for the increased attachment of the jet when a gap exists between members 1 and 25 is that these two members form a converging channel causing an accelerated thin jet to flow through the gap and become attached to the surface, while the remainder of the main jet, as it leaves the trough-shaped member, becomes partially entrained by the thin jet and thereby also caused to follow the curvature of the deflectors surface.

As indicated in FIG. 11, the jet stream tends to be divided by the deflector member itself also, so that a small proportion of the air flow follows the surface of the deflector nearer to the discharge opening 13. The proportion varies with the position of the deflector relative to the discharge opening. In practice a similar effect will occur with the arrangement illustrated in FIG. 2 although it is not indicated in that figure.

FIGS. 13 and 14 show a detail of a further modification in which the jet deflector assembly 14 is angularly adjustable about the longitudinal axis of the jet nozzle. The deflector assembly is supported from a collar 40 which is rotatable about the engine body 10 by means of an electric motor 41 and rubber linkage 42, 43, the motor being carried from the engine body by support struts 44.

,A jet deflector in accordance with the present invention is particularly suitable for use in combination with a jet nozzle having a circular or other discharge opening whose lengthwise and breadthwise dimensions are of the same order of magnitude, as opposed to a slot-like opening which produces a jet in the form of a substantially two dimensional sheet of wide transverse dimension but little depth. In such a combination it is necessary that the deflector shall have an operative position at which the jet is directed between the laterally spaced boundary walls and impinges on the surface, so that the surface at least partly obstructs the free flow of the gas stream.

It will be noted that in each of the embodiments of the invention described herein, the jet nozzle forms such a thick jet and the deflector is movable to an operative position at which it interferes with the greater part of the jet flow.

It has been found that a jet deflector in accordance with the present invention can be positioned at a distance from the discharge opening of a jet nozzle of up to three times the diameter of the nozzle without appreciably decreasing the amount of jet deflection. This property has the advantage that if the deflector element is spaced some distance from the nozzle discharge opening, the gases impinging on its surface will be at a lower temperature than would otherwise be the case, and special high temperature materials may not be necessary for the structural parts of the jet deflector.

What I claim as my invention is:

1. In combination with a jet propulsion power plant having a jet nozzle with a discharge opening for forming an axially-issuing jet, a deflector having a pair of laterally spaced boundary walls and a base surface extending therebetween, and means supporting the deflector behind the discharge opening so that the base surface lies inside the normal flow path of the axially-issuing jet, the base surface presenting a convex longitudinal profile curved in a direction away from the jet so that the jet stream follows the curvature of the surface, and the base surface having a transverse profile which matches the cross sectional shape of the jet stream directed over the surface.

2. In combination with a jet propulsion power plant having a jet nozzle with a discharge opening, a deflector mounted behind the discharge opening, the deflector having a surface which presents a convex profile curved in a direction away from the jet, said surface extending transversely between laterally spaced boundary walls between which the jet is directed so that the jet stream tends to follow the curvature of the surface, such surface having a transverse discontinuity of curvature constituting a detachment edge for the jet stream, and means for rotating the deflector about a transverse axis to vary the eflective length of surface across which the jet stream flows.

3. The combination claimed in claim 2, wherein the curvature of the deflectors surface in the direction of the jet stream decreases continuously from a maximum to a minimum imediately adjacent to the discontinuity.

4. The combination claimed in claim 2, wherein the deflector comprises first and second telescoping sections each having a surface which presents a convex profile curved in a direction away from the jet, the first section being fixed with respect to the jet nozzle, the second section providing said detachment edge, and the second section being rotatably adjustable with respect to the first section by said rotating means for selectively adjusting the position of the detachment edge.

5. In combination with a jet propulsion power plant having a jet nozzle with a discharge opening, a support assembly extending behind the discharge opening, a deflector carried by the support assembly, the deflector having a surface which presents a convex profile curved in a direction away from the jet, said surface having a transverse discontinuity forming a detachment edge for the jet stream, first power means operatively connected with the support means for moving the deflector between an operative position at which the jet stream impinges on the surface of the deflector and a second position at which the deflector is removed from the jet stream, and second power means for rotatably adjusting the deflector with respect to the support means about a transverse axis to control the position of the detachment edge.

6. A jet deflector for use with jet propulsion power plant having a jet nozzle with a discharge opening, comprising an articulated support structure, a deflector member carried by the articulated support structure, the deflector member having a surface which presents a convex profile in the direction of jet flow and extends between laterally spaced boundary walls between which the jet is directed so that the jet stream tends to follow the curvature of the surface, and power means operatively connected to the support structure for moving the deflector member to and from an operative position at which the jet impinges upon and is directed across said surface.

7. A jet deflector according to claim 6, in which the deflector member is associated with a shroud which shrouds the part of the deflector surface across which the jet stream is caused to flow, the shroud defining with said surface and boundary walls a passage for the entrainment of air.

8. A jet deflector according to claim 7, in which the shroud is formed with a leading edge having an inwardly directed lip, and a trailing edge.

9. A jet deflector for use with jet propulsion power plant having a jet nozzle with a discharge opening, comprising a deflector member, an articulated support structure carrying the deflector member, power means coupled to the articulated support structure and operable to move the deflector member to and from an operative position, the deflector member having a surface which presents a convex profile in the longitudinal direction of jet flow and a transverse profile which is matched to the crosssectional shape of the jet, the surface extending transversely between laterally spaced boundary walls between which the jet is directed when the deflector member is in its operative position so that the jet stream tends to follow the curvature of the surface, said surface having a transverse discontinuity of curvature forming a detachment edge for the jet stream, and means for adjustably rotating the deflector member about a transverse axis to vary the angular deflection of the jet.

10. In combination with a jet engine power plant having a jet nozzle with a rearwardly directed discharge opening, a movable support structure, a jet deflector mounted on the support structure, the jet deflector having a surface across which the jet stream is directed and upon which the jet stream impinges when the deflector is in an operative position, said surface presenting a convex profile curved in a direction away from the jet, and means for actuating the support structure to move the jet deflector to and from its operative position.

11. In combination with a jet engine power plant having a jet nozzle, the jet nozzle comprising a body with a longitudinal axis and a rearwardly directed discharge opening, a support structure articulately connected to said body, a jet deflector carried by the support structure and angularly adjustable thereon about a transverse axis, the jet deflector having an attachment surface which presents a convex profile curved away from said longi tudinal axis towards a transverse discontinuity forming a detachment edge for the jet stream, said surface extending transversely between laterally spaced boundary Walls between which the jet is directed when the deflector is in an operative position, the transverse profile of the surface being matched to the cross-sectional shape of the jet, a shroud member combined with the deflector and shrouding said surface to define therewith a passage for the entrainment of air, first power means operatively connected to the support structure for selectively moving the jet deflector to and from its operative position, and second means operatively connected to the deflector for selectively varying the angular adjustment of the deflector about said transverse axis, whereby to adjust the position of the detachment edge for varying the jet deflection.

12. A jet propulsion power plant including a jet nozzle, the jet nozzle having a discharge opening whose lengthwise and breadthwise dimensions are of the same order of magnitude, a deflector mounted behind the discharge opening, the deflector having a surface which presents a convex profile curved in a direction away from the jet and extends transversely between laterally spaced boundary walls, and means for positioning the deflector so that said surface lies inside the normal flow path of the jet and the jet is directed between the boundary walls and impinges upon the said surface.

13. In combination with a jet propulsion power plant including a jet nozzle with a discharge opening whose lengthwise and breadthwise dimensions are of the same order of magnitude, a deflector mounted behind the discharge opening, the deflector having a convex profile which is curved in a direction away from the jet and extends between laterally spaced boundary walls, an articulated support structure carrying the deflector, and means operatively connected with the support structure for moving the deflector into a position at which the jet is directed between the laterally spaced boundary walls and impinges upon the surface so that the jet tends to follow the curvature of the surface.

14. In the combination claimed in claim 1, a troughshaped jet dividing member having a concave upper surface, and a convex lower surface spaced by a small amount from the surface of the jet deflector, said member being positioned adjacent to the jet deflector and adapted to divide the jet stream so that a relatively thin jet impinges upon the jet deflector surface and becomes attached thereto, a part of the main jet becoming entrained by the thin jet on leaving the concave upper surface.

15. The combination claimed in claim 1, including means for angularly adjusting the jet deflector about the longitudinal axis of the jet nozzle.

16. The combination claimed in claim 14, in which the deflector member is associated with a shroud which shrouds the part of the deflector surface across which the jet streamis caused to flow, the shroud defining with said surface and boundary walls a passage for the entrainment of air.

References Cited UNITED STATES PATENTS 2,702,986 3/1955 Kadosch et a1. 239-26519 2,812,980 11/1957 Kadosch et al. 60230X M. HENSON WOOD, JR., Primary Examiner M. Y. MAR, Assistant Examiner US. 01. X.R. 60-230; 239 s11, 513, 523; 244-42 

